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Latest blog entry: My hangar...
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At first I was thinking your pretty brave to fly around so many tall trees and then I see the precision flying and sense of control exuded from the planes behaviour. Skills man.. skills! Did you even get over a house?I'm betting your neighbours love watching the flying, not the planes. |
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I was seeing a lot of resistor talk back a few pages where it almost appeared as if watts and ohms were being used interchangeably. Please be careful with that, they are not the same, not by a long shot.
Yes, your caps will be fine, they will charge up to whatever voltage your batteries are at. As long as the battery voltage is below the rating listed, you should be fine (not considering any sort of transient spikes from some kind of back emf, which shouldn't happen, so don't even worry about them.) For the cap charge circuit, see attached diagram. A 50V battery bus on a 1kOhm resistor would give a 50mA charge current and need a resistor of ~2.5W in power rating, a bit large, but doable. This rating (1kOhm) is the smallest I would recommend. You can go higher, by all means use a larger value (in Ohms) as it will allow you to use a smaller resistor in terms of power rating (cheaper), just keep in mind that a larger resistor (Ohms) will take longer to charge up the capacitor bank. V=IR, It's the law (I have that printed on my business cards, no joke.) edit: DAG, sent you an email, I'm in the Ohio area through Sunday and I've got the prototype with me if you want to see it. Not sure how your week is looking with the event Sat., but I'll be in the Dayton area by 11am or so tmrw and will be there till sometime Sunday as my senior design team competes here:http://www.ion.org/satdiv/alc/ Our entry: http://picasaweb.google.com/hydesea/AutoMow# If anyone here is local to the area, feel free to stop by and say hi. |
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United States, AZ, Scottsdale
Joined Aug 2008
48 Posts
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Hi
The cap charge circuit will work to prevent large sparks but I read somewhere in another thread that there is a possible problem when it is used with certain brands of ESC's. From memory, the ESC will initiate its startup sequence before the caps have fully charged to the battery voltage and as a result a lower cutoff point for the low voltage cutoff will be set into the ESC than the number of cells in the battery would warrant. This will not be a problem if you never fly long enought to drain the battery to a low level or use a type of ESC that sets the low voltage cutoff point via an initial setup program. Just wanted to make you aware of this in case it applies to any of your projects. John W. |
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Hey all,
Little set back, as you know everything is weight on this project. The small circuit board I made for my caps is a heavy turd. So I am going to plan "B", what plan "B" is I have no idea yet. And just an FYI, I see a bunch about resistor, I am only fly 6 cells on this bird, do I really care, I could see if it was my 1919 with 10 or 12 cells, but 6 cells?? Also today I am slammed with work again, and tonight I have to start getting set up for the RC Airshow this weekend. I am making a APU cart, I bought a small (in size not in price) Honda generator that will be powering a deep cycle 12v marine battery. I wish I could see that the end is near with all the money I keep dumping into this hobby, but I just can't see it . What will be cool is I can get about 5-10 charges of the deep cycle 12v, then when needed I just fire up the generator. In all I will have a $3,000.00 in the APU with the power system, and chargers. And if I am ever at a RC event and anyone needs power for their chargers I will be the guy. My generator can top of my 12v deep cycle at 15 amps. Basically I have a Generator, Car Battery Smart Charge that will charge at 2-10-15 amps, 12v deep cycle battery, my power ports, and then my chargers, and a 100' extension if I want to leave the generator back by the trailer.Rock on! Dag It is amazing how dumb these oil people are. To stop the leak is easy, but no one wants to think outside the box. If you take a Kevlar Balloon pack it tight like a airbag on a car, then push it down about 500 yards into the well, then set off a couple of nitrogen cartages at let’s say 200PSI, and BAMB! Leaked stopped. |
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![]() than a building. Last year we had some fun where we had a kid with 2 flags acting like he was guiding me in for a landing like on a carrier. We where all having a blast and each kid took turns, some knew that it was their skill at the flags that made me have such a good landing . In the 6 years of flying of the street I have only had one problem. At the 4th airshow about 5 years ago I would go up about 200' and do a flat spin, I would have all the kids count, if I made it to 10 I hit my goal, well I did not get enough altitude and on my 10th spin I knew I had really screwed up and let myself get way to low, so I parked my biplane in the tree across the street, just pulled the landing gear off, and with some hot glue was flying the next day. The reason for the next was I went up the tree and got the plane, but it was the next day that my son went back up the tree and found the landing gear. Needless to say, I go much higher now, and safety is always 110% first with me and flying. And if I do ever get over any houses, it is only 2, and they love my planes and kids![]() ![]() .I see many that can just fly a plane, but I notice many let the plane fly them, if you cannot keep heading on ground roll you need more practice. If you cannot land on a spot 20' in length, you need more practice. I am a big nerd and for a long time kept count of how many flights I have flown, I quit counting at about 2520, that might not sound like a lot for flying 30 years, but it is a bunch, if my math is right, about .23 times a day is what is averages out to. I just love to fly. Rock Onward ![]() ![]() ![]() Dag |
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Milton, WI USA
Joined Dec 2007
522 Posts
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Oil Leak & Pressure
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Good idea Dag, but at the depth they are working at the sea pressure is over 2000 lbs/sq in. Sea water is 44.4 lbs/per sq in per 100 feet. Tom |
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![]() ![]() , I know that the pressure is huge, but is there not a state that the forces become equal as your against an opposing force? When I say 200PSI I meant over what other outside force is present, that is why I said Kevlar, I know it may be a stupid idea, But I have seen Kevlar used at incredible loads. But I may have just inadvertently ![]() derail my thread again. Rock on! Dag |
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Joined Sep 2009
36 Posts
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Dag, some years ago, I was using a 32 cell nicd pack for one of my planes, at the field I used a 12v, deep cycle marine battery like you. I could get about 2 charges and then it took forever to get the third. I was messing around one day and put my astro watt meter between the 12v batt and my charger(SR smart charger) during a charge, it showed a 23 amp draw on the 12v batt. I then knew why I was only getting a couple of charges, out of the batt before needing a recharge. I was charging at 5-6 amps for the pack.
Just something to think about Bob |
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I know what you mean, my 4 6600 packs for my 1919 pulls my 12 volt down after 4 charges. That is why I have a gen-set with a AC battery charger to keep my Deep Cycle topped off. At SEFF I saw many cool gen-set set-ups. I tested the set-up on Monday in my garage. I will have 3 chargers that will draw on my 12v, and the gen-set to keep my 12v charged. I am wondering if I can pull more than my 15 amp car battery charger can keep my 12v charged at. My Gen-set will put out 16 amps at 120volts continuously. So the test will be will I pull more out of the 12v deep cycle battery than my gen-set can keep up with. Remember I only fly my big stuff about 4-5 times in a 8-10 hours day. So the charger will have all day to keep working. Rock ON! Dag |
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